<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<input type="text" id="d1" placeholder="学生姓名">
<input type="text" id="d2" placeholder="班级">
<input type="text" id="d3" placeholder="学号">
<input type="button" value="添加" onclick="f()">
<table border="2">
<caption>学生信息</caption>
  <tr>
    <th>姓名</th>
    <th>班级</th>
    <th>学号</th>
  </tr>

</table>

<script>
    let d1 = document.querySelector("#d1");
    let d2 = document.querySelector("#d2");
    let d3 = document.querySelector("#d3");
    function f() {
        //创建tr和td
        let tr = document.createElement("tr");
        let name = document.createElement("td");
        let bj = document.createElement("td");
        let xh = document.createElement("td");
        name.innerText=d1.value;
        bj.innerText = d2.value;
        xh.innerText =d3.value;

        //把td装入tr
        tr.append(name,bj,xh);
        let table = document.querySelector("table");
        table.append(tr)
    }
</script>

</body>
</html>